[x86] Re-generate a bunch of the v4f64 test cases with my new script.

This expands the integer cases to cover the fact that AVX2 moves their
lane-crossing shuffles into the integer domain. It also adds proper
support for AVX2 run lines and the "ALL" group when it doesn't matter.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218206 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Add some more comprehensive tests for v4f64 blending.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218207 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Teach the new vector shuffle lowering of v4f64 to prefer a direct
VBLENDPD over using VSHUFPD. While the 256-bit variant of VBLENDPD slows
down to the same speed as VSHUFPD on Sandy Bridge CPUs, it has twice the
reciprocal throughput on Ivy Bridge CPUs much like it does everywhere
for 128-bits. There isn't a downside, so just eagerly use this
instruction when it suffices.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218208 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Explicitly lower to a blend early if it is trivial to do so for
v8f32 shuffles in the new vector shuffle lowering code.

This is very cheap to do and makes it much more clear that anything more
expensive but overlapping with this lowering should be selected
afterward (for example using AVX2's VPERMPS). However, no functionality
changed here as without this code we would fall through to create no-op
shuffles of each input and a blend. =]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218209 91177308-0d34-0410-b5e6-96231b3b80d8